<body>
  <input type="submit" value="Check" onclick="doCheck(); return false;">
  <script>
  	function doCheck() {
  		if(window.opener.lobo_property) {
  			alert('Opener property found');
  		}
  		else {
  			alert('Opener property not found');
  		}
  		if(window.alt_opener.lobo_property) {
  			alert('Alt-Opener property found');
  		}
  		else {
  			alert('Alt-Opener property not found');
  		}
  	}
  </script>
</body>
